Method of electric welding.



o H. WILSON. METHOD OF ELECTRIC WELDING. APPLICATION FILED JULY9| I915- RENEWED MAY 10. 1916.

1 87,4 1 0 Patented June 13, 1916 L L INVENTOR. WITNESSES: I

" MY' ZZZ ATTORNEYS.

UNITED STATES PATENT OFFICE.

DAVID WILSON, OF PATTERSON, NEW JERSEY.

METHOD OF ELECTRIC WELDING.

Specification of Letters Patent. P t t June 13, 1 1

Application filed July 9, 1915, Serial No. 39,012. Renewed May 10, 1916. Serial No. 96,537.

To all whom it may camera Be it known that 1, DAVID H. WILSON,

citizen of the United States, and resident of Paterson, in the county of Passaic and State of New'Jersey, have invented certain new and useful Improvements in Methods of Electric Welding, of which the following is a specification.

My invention consistsof a new method of electric welding with an arc.

. It includes two features of the welding current, which may be used separately or jointly as desired, one feature relating to potential and the other to a critical temperature for the particular welding alloy 4 used.

Heretofore, it has been the custom to employ a current of upward of 60 volts .of considerable length, the resistance in the circuit being reduced correspondingly, before the arc breaks. In other words, the operator has been allowed wide limits of potential and length of arc'with which to.

perform the welding operations. While it has been possible to cut down at the arc terminals, the comparatively high voltages used at the generator, the automatic resistance varying devices in the circuit have permitted the operators drawing long' hightemperature arcs between the terminals;

1 One objection of the long burning arc has been the violent electrical action upon the welding metal, preventing an even flow of metal from the welding electrode across the arc to the work and damaging the char.- I acter of the weld. It is easier for an op-- erator to weld with a long high voltage arc than with alow voltage one. The are from a high voltage circuit breaks less easily since it may be varied in length much more than that from a low voltage circuit. When the current on the mains has a high voltage, the result is that while there may be wide fluctuations a long burningarc prevails. The d-amaglng efiect of the long hot arc has not been understood heretofore. Large amperages have contributed to the damage. The heatof the are results in the formation 1n the o1nt of small craters surrounded by slag thus damaging the weld. Sometimes a comparatively small variation of the cur-' rent causes the formation of craters and slag. Furthermore, if the heat of the-arc is reduced below the proper temperature, the weldlng metal fails to adhere to the work. Furthermore, the long are causes a violent electrical action on the flow of metal preventing a smooth-regular flow.

from welding with the long burning arc and thus injuring the welding metal. For example, I supply a current having a voltage .of 18 to 24 or thereabout across the are terminals. To allow for the drop of voltage due to line connections and conductors a main line constant potential of 35 'VOltS or thereabout is satisfactory.

By employing suchacurrent for are welding, the resistance of the welding terminals is suflicient to check any unduerush of current particularly if both are fusible welding metals adapted to flow and create a solid welded joint; and yet there'is suflicient voltage with which to draw the are. With such a current subsequent reduction of circuit resistance is unnecessary. In fact, I find it desirable to increase the circuit resistance if too great an amperage is supplied over the mains, to a point that will permit the flow of the desired current for the proper welding heat. The best heat for the arc varies somewhat owing to the conductivity and melting temperatures of the differentmetals that may be subjected to welding, as well as to the size of the welding electrode.

- Another object of my invention is to perform a welding operation by means-of a current that will create the temperature best suited for welding. Metals and alloys have what may be called critical temperatures, that is,-temperatures at which they may be 'used for welding purposes with the best re sults. Some" metals have one temper t re and other metals have other temperatures. The critical temperatures of the welzfifigmetals vary with .the different constituents, or some of them, of which they are composed; The size of the wire may also affect these factors.

The temperature of the arc depends u on the watts of current traversing the are. he critical temperature may be attained by varyin either the potential or the current. Since it is objectionable to use a high potential, it is better to secure the critical temperature by a variation of the amperage 'of the current. For example, the critical temperature for a welding electrode composed of steel wire, .15" in diameter, having about 20% carbon, and .40% manganese, is obtained by employing a current having an amperage of about 125 at the potential above described. As the size of the Welding wire increases, there is a tendency for the por- 'tions of the wire near its perimeter to become too hot and slag formation and weak-v ened welds result. So that a small welding wire has advantages over alarge one. .15 wire gives excellent results flowing as a mass in an even plastic state across the are.

My invention which consists first in the low voltage current from the vgenerator which prevents the formation of the long burning arc; and second, the maintenance of the.heat of the are at substantially .the critical temperature of the welding alloy under the conditions of use, eliminates m'any obstacles and assists in the attainment of a substantially perfect weld. The critical temperature is such as will cause the transfer of metal across the arc in a more or less plastic state. H r r I have discovered that arc welding fluxes are not .only useless but positively detrimental for low potentialwelding.

One, or the objects of my method is to provide the facilities for an even and smooth flow of metal so that the metal which leaves the .electrode is deposited upon the work with the least possible alteration in its charac r.

l ests have been made of many different.

fluxes. When a flux is used in arc welding,

- thematerials in. the flux are carried into the weld and weaken it; so that instead of scavenging the welded metal as intended, they. add impurities to it. My low .voltage weldin g current overcomes the difliculties heretofore encountered in securing a pure weld without the use of a. fiux. Means, including fluxes, have'also been employed to surround the welding arc with a hlanketof gas of such a character as to prevent high oxidation. Such means have been useless for the purpose of assisting in arc welding v operations.

method which permits the elimination of fixes and gasblankets accomplishes the most erfect weld that has so far been atta'iiied In the drawings: Figure 1 shows a diagram of the circuits and apparatus capable of supplying an even current. Fig. 2 shows a section upon line AA in Fig. 1.

In Fig. 1 is shownapiece of metal 1, constituting the work. This piece of metal may be fractured as shown; and it may be part of a; boiler or other piece of mechanism or apparatus intended for repair. It may represent a part intended for joining in a manufacturing'process, or it may be any material to which my invention may be ap plied. This piece of metal 1, is connected through the conductor 2 to the source of welding current 3 which may, for example,

I be the negative pole of a bipolar generator.

The tool holder 4 is adapted to have secured to it a metal electrode 5, which may be of any suitable steel or alloy, in electrical connection with the conductor 6, which may be a cable as indicated at 7. This conductor 5 is connected through the main regulating pile 8 and solenoid 9 to the positive pole 10 of the generator. V

The operation of the solenoid 8 is delayed by the dash pot 11. To the core of the solenoid is secured a rod 12 at the other end of which is fixed a plate 13 fittin freely within a this delay is to maintain'the circuit ofthe carbon pile at a low resistance until the operator has had an opportunity to separate the welding tool 5 from the work 1. During the drawing of the are or soon after, the solenoid overcomes the dash pot and increases the resistance up to the requirements of the welding are.

It is thus apparent that when the electrode 5 is, brought intocontact with the metal work 1, the circuit established from the of electric current.3 and 10 over the circuits abo've described, permits the passage first of an amount of current sufficient to establish the desired arc. The current is then reduced after the terminals'become heated, the pile resistance being increased for the'purpose. It may preferably be adjusted to supply a variable amount of current from say, 200 amperes, down to any amount,-

25, that may be desired by the operator.' In order that he may select the adapted to. come into contact with elther one of the two contacts 18 or 19. If the operator I contact 18, he selects the desired normal repull them toward each other.-

sistance of the pile byoperating the motor 20 in the following circuit; source of current 3, conductors 2 and 21, switch 17, contact 18, circuit closer 22, field coil 23 of the motor, the armature of the motor, conductor 24, to the terminal 10. This circuit causes the motor to rotate in such a direction as to advance springs 25 and 26 or otherresilient .means, to the left in the figure sothat the rollers 27 and 28 travel toward the pile track 29 and the roller 28 upon the lever 30 (which is fulcrumed upon the fixed pivot 31 and engages the end 32 of the pile 9) so that the spring exerts a reduced compression upon the pile against the adjustable abutment 33, thereby increasing the resistance of the pile. Inthis' apparatus, the motor 20 is provided with a pinion 34, driving the gear wheels 35 and 36. The springs '25 and 26 are fastened to the journals 37 and 38 of the rollers 27 and 28, tending to The upper journal 37 is adapted to freely slide in the slot 39 so that theroller is adapted to exert a fairly constant pressure upon the lever 30 and a varying pressure upon the pile. This lever is fulcrumed at 31 and engages end plate 41 of the pile. The plate exerts a pressure upon the pile, pressing the various disks of the pile into closer engagement and against the adjustable abutment 33. It will be seen that the operator in closing the switch lever 17 to the contact 18 may cause the springs 25 and 26 .to be carried along the lever 30, so that the while its tension or pull is not greatly altered, its effect upon.

the pile is greatly altered. In this way, the operator is enabled to vary the amount of current supplied through the pile.

If the operator leaves the switch 17 in engagement with the contact 18 too long, the lug 42 upon the carrier 43 engagesran automatic circuit breaking lever 44 pivoted at 45 and switches it to the left against the compression spring 46 until the pressure of the spring is exerted in a direction to the right of thepivot 45 thus throwing the lever over. This causes the arm 47 to engage lever 48 pivoted at 49v and causes it to break the circuit between the contacts 22, sothat the, motor 20 stops working. When the operator desires more current for his work, he shifts the lever 17 to the contact 19, thereby switching the current from the winding 23 of the field of the motor to the winding 51 of the field of the motor, causing the motor to rotate in theopposite direction. The motor now operates the travelerv43 to the right and causes the springs 25 and 26 toincrease the pressure upon the pile, thereby reducing its resistance and increasing the current therethrough. To pie-- vent the operator from injuring the construction by a too prolonged operation of the motor, the lug 42 engages the lever 52,

average quantity of current desired for his 9, the roller 27 traveling upon the fixed work, the main regulating solenoid 9 maintains the current so that it is substantially even at all times. The operator may adjust the pressure upon the pile so that at all times the disks of the pile are in such intimate contact with each other as to avoid sparking or injurious heating. If the car-- bon disks should not make uniform contact throughout their surfaces, there would result a detrimental local heating at the points of contact.

The more uniform the contact is throughout the area of the disks, the greater the amount of current which can pass through the disks without injurious heating and the less the consumption of the pile and the greater its life. We have found it desirable to employ a substantial pressure upon thedisks as a minimum premure, and to vary the same to a substantially high pressure. I

The spring pressure upon the lever,.which transfers the pressure to the carbon pile, may if desired, be fifty pounds or more. As the spring travels away from or toward the fulcrum, the pressure upon the pile tends to be correspondingly varied; When the solenoid is energized, the pressure upon the disks is affected to an extent determined by the amount of current flowing through the sole noid winding. The pressure of the spring action upon the pile, however, isnot entirely removed, since the solenoid action is never strong enough to overcome the full force of the'traveling spring. I do not limit my invention to these specific pressures for various otherv pressures may be employed, all depending upon the amount of current to be acommodated and the capacity of the pile.

The object of the construction just referred to is to keep the disks of the pile in such intimate or uniform contact throughout their surfaces as to prevent injurious heating under all conditions of use.

If the res stance at the arc increases, due

' to the uncertainty of the operators manipulation of the tool,'it causes a reduction of the. flow of current through the solenoid, which exerts a smaller pull upon its core resulting in a lighter pull upon the outer end of the lever, so that the carbon pile issubjected to more compression from the springs 25 and 26. When, however, the resistance of the particular welding metal occurs the otential and current values remaining su stantially constant.

9. The method of electric welding which consists in transferring Welding metal across an are by means of a continuously low voltage current adapted to prevent v burning.

10. The method of electric welding which consists in transferring a flux free welding metal across an are by means of a continuously low voltage current adapted to prevent burning.

11. The method of electric welding which consists in transferring welding metal 15 across an are free from slag by means of a continuously low voltage current.

12. The method of electric welding which consists in transferring welding metal acrossan arc in a plastic state.

Signed at New York, in the county of New York and State of New York this 2nd day of June, A. D. 1915.

, DAVID HQWILSON.

Witnesses:

WM. W. WILLIAMS, A. L.\TRAVIS. 

